Visual information is of the utmost importance to road users. In darkness, both public lighting and vehicle lighting help road users take stock of the traffic situation and help them to be seen by others. Installing public lighting leads to a 50% reduction in the number of nighttime injury crashes. Disavantages of public lighting are, among other things, the risk of collisons with lamp posts, light pollution and the costs of material, maintenance and energy consumption. The road safety effects of a reduction in illuminance level on motorways vary according to the traffic situation.